Angle-scanned photoelectron diffraction chemisorption study of c( 2 × 2)-O on Ni( 1 ML)/Cu( 100)

A heteroepitaxial monolayer deposited on a suitable single-crystal substrate is exploited as the source of the primary photoelectron wave in the determination of chemisorption site geometries using an angle-scanned forward scattering approach. The method is applied to the study of c(2 × 2)-O on Ni (1 monolayer) deposited on Cu(100). In agreement with literature data, oxygen atoms occupy fourfold hollow sites, with a Ni-O distance of 1.92 ± 0.04 A and with an angle between the Ni-O bond and the surface of 20 ± 1°. The major point is that such information is deduced directly from the experimental raw data without any theoretical simulation.